Upper Critical Field in the Molecular Organic Superconductor (DMET)$_{2}$I$_{3}$

We report the temperature dependence of the upper critical magnetic field in the quasi-one-dimensional molecular organic superconductor (DMET)$_{2}$I$_{3}$, for magnetic field applied along the intrachain, interchain, and interplane directions. The upper critical field tends to saturation at low temperature for field in all directions and does not exceed the Pauli paramagnetic limit. Thus the superconductivity appears to be conventional spin singlet, in contrast to the status of the isostructural Bechgaard salts. Furthermore, we will discuss a magnetic field-induced dimensional crossover effect in the normal metallic state leading to a magnetoresistance minimum for the field parallel to the most conducting plane. This result will be useful to understand the nature of superconductivity in the molecular organic conductors.